Atorvastatin calcium is known by synonyms like [R-(R*,R*)]-2-(4-fluorophenyl)-σσ, 6-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino) carbonyl-1H-pyrrole-1-heptanoic acid hemicalcium salt; (βR,δR)-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-, 1H-Pyrrole-1-heptanoic acid hemicalcium salt; [R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-, 1H-Pyrrole-1-heptanoic acid hemicalcium salt or (βR,δR)-2-(p-Fluorophenyl)-β,δ-dihydroxy-5-isopropyl-3-phenyl-4-(phenylcarbamoyl)pyrrole-1-heptanoic acid hemicalcium salt.
The hemicalcium salt of [R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-, 1H-Pyrrole-1-heptanoic acid, a synthetic HMG-CoA reductase inhibitor, is used for the treatment of hyperlipidemia and hypercholesterolemia, both of which are risk factors for arteriosclerosis and coronary heart disease. Open dihydroxy carboxylic acid, lactone and various salt forms of [R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-, 1H-Pyrrole-1-heptanoic acid have been synthesized.
U.S. Pat. No. 5,273,995, teaches that [R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-, 1H-Pyrrole-1-heptanoic acid has surprising inhibition of the biosynthesis of cholesterol. The calcium salt of [R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-, 1H-Pyrrole-1-heptanoic acid (2:1) (Formula I)
is more suited to formulations and has been recommended as a drug.
U.S. Pat. Nos. 5,003,080; 5,097,045; 5,103,024; 5,124,482; 5,149,837; 5,155,251; 5,216,174; 5,245,047; 5,248,793; 5,273,995; 5,280,126; 5,298,627; 5,342,952; 5,385,929; 5,397,792; European Patent 409,281; and WO 89/07598 describe various processes and key intermediates for preparing atorvastatin.
WO 97/03958 and WO 97/03959 disclose novel crystalline forms of atorvastatin calcium designated as Form I, Form II, Form III and Form IV and methods for their preparation, providing more favorable filtration and drying characteristics.
WO 97/03960 and U.S. Pat. No. 6,087,511 describe procedures for converting the crystalline form of atorvastatin calcium to an amorphous form. The processes disclosed therein involve dissolving Form I atorvastatin calcium in a non-hydroxylic solvent like tetrahydrofuran or a mixture of tetrahydrofuran and toluene.
WO 00/71116 describes a procedure for converting the crystalline Form-I by dissolving it in a non-hydroxylic solvent like tetrahydrofuran and precipitating amorphous atorvastatin calcium by the addition of nonpolar hydrocarbon solvents like, n-hexane, cyclohexane or n-heptane, for example.
It is therefore one object of the present invention to provide a novel process for the preparation of atorvastatin calcium, unique with respect to its simplicity, cost effectiveness and scalability.